Method of and apparatus for making radiographs of body layers



H. CHAOUL Oct. 18, 1938.

METHOD OF AND APPARATUS FOR MAKING RADIOGRAPHS OF BODY LAYERS Filed June 2?, 1935 Patented Oct. 18, 1938 UNITED STATES PATENT OFFICE METHOD OF AND APPARATUS FOR MAKING RADIOGRAPHS F BODY LAYERS Henri Chaoul, Berlin, Germany Claims.

This invention relates to a method of and apparatus for making radiographs of body sections. Radiographs of sections of the body where the latter are relatively thin measuredin the direc- 5 tion in which they are radiographed are generally suificiently informative from the point of view of diagnosis. For the diagnosis, however, of parts of the body which are relatively thick measuredin the direction in which the radio graph is made, such as the spinal column for example, it is found that a radiograph of a single section is not sufiicient. It is therefore customary to radiograph separately several parallel sections of such parts of the body. The making of 18 a plurality of such separate sectional radiographs, however, takes considerable time and requires a large quantity of film material and the X-ray dose administered to the patient is multiplied. 20 In the present invention it is sought to overcome these difiiculties by producing upon a film in a single collective picture an infinite number of parallel body sections located within a body layer of more or less thickness. In the embodi- 25 ment of the invention herein shown and described for illustrative purposes this result is obtained, for example, by moving the axes of rotation or joints of the apparatus elements which are in the plane of the section radiographed, 0 which apparatus elements transfer the movement of the X-ray tube to the light sensitive layer, relatively to the support or plate upon which rests the body to be reproduced positively at least once with the movement of said tube 35 and of the light sensitive layer during the exposure, said movement being equal to the thickness of the body layer to be reproduced. In this operation the distance of the focus from the film will preferably remain unchanged in order that 40 the pictures obtained of all the body sections may be enlarged to the same degree. As the X- ray pictures of parts of the body located without the plane-parallel body layer will be washed out, a clear and extremely informative X-ray picture 45 for diagnostic purposes, of the plane-parallel body layer, will be obtained.

The invention and its aims and objects will be readily understood from the following description taken in connection with the accom- 50 panying drawing of one illustrative form of apparatus for carrying out my novel method, said drawing being largely diagrammatic and the true scope of the invention being more particularly pointed out in the appended claims.

55 The present invention is an improvement or further development of the type of method and apparatus illustrated and described in the pending application of Grossman, Ser. No. 721,794, filed April 21, 1934, now Patent No. 2,110,953

issued March 15, 1938, wherein, in making a ra- 5' diograph the X-ray tube and the central axis of the light sensitive layer are rotated in unison in opposite directions, in a plane perpendicular to the plane of the body section to be radiographed about a fixed axis, located in the plane of said 10 section to be radiographed said light sensitive layer being always kept parallel to itself by a parallel link motion of any suitable construction. Reference is made to said prior application for a more detailed description of the general structure, mode of operation and advantages of this type of apparatus, only those parts being herein described which are necessary to the understanding of the present invention.

In the drawing, Fig. 1 is a front view partly diagrammatic of one illustrative embodiment of the invention;

Fig. 2 is a side view of the illustrative embodiment of the invention as shown in Fig. 1.

Referring to the drawing, a two-armed lever 2 carries at one end an X-ray tube 4 and at its other end a shaft 6 upon which is freely rotatable the light sensitive layer 8, which as already stated,

is maintained always parallel to itself by a parallel link motion of any suitable and conventional construction. Said lever 2 is rotatable about a shaft it! carried by a quadrangular carriage l2 slidably guided in a slot 54 of a vertical frame 16. Vertical movement of said carriage I2 is effected by a screw-threaded spindle I8 with which said carriage has screw-threaded connection in any suitable manner. The shaft M of said lever 2 carries an interiorly toothed sector 28, the teeth of which mesh with those of a gear 22 of a gear transmission driven by the drive 4.0 shaft 24 of an electric motor 26 mounted upon said carriage l2.

The screw-threaded spindle I8 is adapted to be driven from an electric motor ,28 through a gear transmission 30, said motor being mounted upon the frame !6. Both motors 26 and 28 are connected with each other and to the main 4!) by conductors 32, 34, 36 and 38 and are controlled by a Switch 42.

In operation, upon closure of said switch 42 both motors 26 and 28 will be simultaneously energized. This, causes the double armed lever 2 to be swung about its axis In from one extreme end position shown in full lines in the drawing into the opposite end position shown in the dotted line 44. During this rotary movement of said lever 2, the motor 28 will through the transmission above referred to, cause said spindle I8 to turn sufficiently to move the slide l2, and with it the shaft H! of said lever 2 a certain distance vertically in said frame Hi. When the lever 2 reaches its dotted line position 44 it actuates a contact in the circuit of the electromagnet winding of said automatic switch 42 thereby closing said circuit and de-energizing both motors 26 and 28. The extent of movement thus imparted to the shaft may be varied in any suitable manner, for example, by changing the ratio of the gearing 30 or by varying the number of revolutions of the motor 28 by any suitable and conventional means with which such motors are usually provided. The extent of this vertical movement of said shaft will always be so adjusted that it shall equal the thickness of the body layer to be reproduced. If only a single body section is to be radiographed the motor 28 will be cut out. It is clear that the invention contemplates movement of said shaft H] relatively to the plate upon which the body the sections of which are to be radiographed is supported, that is to say said plate could be moved vertically instead of said shaft, and electromotor 28 could be connected by any suitable and conventional transmission with said plate for this purpose.

Said shaft 1-0 of said two-armed lever 2 could be connected by suitable mechanical means with said spindle [8. In such case the ratio of the transmission means of said connection would be adjustable.

. displaced therewith parallel to the double-armed lever 2. The relation of the distance of the focus from the plane of the section to the distance of the plane of the section from the film will vary continuously with the position of the plane of the section. In such case successive sections will be reproduced in continually increasing or in continually decreasing size. In this way what may be called a central projective representation of the plane parallel body section is obtained.

It will be apparent that the invention is equally applicable to apparatus for making radiographs of body sections, in which the X-ray tube and the picture receiving light sensitive layer execute similar movementsin parallelism to each other and to the body section to be produced and along a straight line, a circular path, a spiral or the like. In such case either the plate upon which the body to be reproduced is supported, or the joints of the links which are located in the plane of the body section to be reproduced and by which the movement of the X-ray tube is transferred to the picture-receiving light sensitive layer, must be positively moved with the movement of the X-ray tube.

I am aware that the invention may be embodied in other specific forms without departing from its spirit or essential attributes, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim:

1. Method of radiographing body layers by making a radiograph of a plurality of parallel sections thereof, which comprises making an exposure of the body layer to be radiographed; during said exposure moving the X-ray focus and the film holder in unison in opposite directions upon opposite sides of said body layer and relatively to a shaft located in a plane that is perpendicular to the plane in which said X-ray focus is moved and parallel to the body layer to be radiographed; maintaining said film holder always parallel to the body layer to be radiographed and directing the central beam of the X-ray always upon the same point of said plane containing said shaft during said movement of the X-ray focus and film holder; and during and in unison with said movement of the X-ray focus and film holder moving said shaft parallel to itself relatively to the body layer to be radiographed and perpendicularly to the plane of said film holder, throughout the thickness of said layer to bring the plane containing said shaft successively into coincidence with the difierent sections of said layer.

2. Method of radiographing body layers which comprises moving the X-ray focus and film holder in unison relatively to a point located in a plane that is parallel to the body layer to be radiographed during the exposure to efface interfering shadows; during said movement maintaining the film in said film holder always parallel to said body layer; and simultaneously with said movement and in unison therewith relatively moving said point and said body layer perpendicularly to said body layer through a distance corresponding to the thickness of said body layer, to cause said plane containing said point to coincide successively with the different sections of said layer.

3. Apparatus for radiographing body layers comprising an X-ray tube; a film holder; a support for said X-ray tube and said film holder; said support being movable relatively to a point located in a plane parallel to the body layer to be radiographed to cause said X-ray tube and film holder to travel as a unit in opposite directions relatively to said body layer, in making the exposure means to maintain the film in said film holder always parallel to said plane during the exposure, whereby each ray of said X-ray tube passing through any point of said plane will always fall upon the same spot of said film throughout the exposure; said X-ray tube being mounted to direct the central beam therefrom always upon the same point of said plane during the exposure; means to move said body layer supporting means relatively to said point and perpendicularly to said body layer and connected to be operated simultaneously and in unison with the travel of said X-ray tube and said film holder in opposite directions relatively to said body layer; and means to limit the relative movement of said supporting means and point.

4. Apparatus for radiographing body layers comprising, an X-ray tube; a film holder; supporting means to support a body layer to be radiographed between said X-ray tube and said film holder; a shaft located in a plane parallel to the body layer to be radiographed about which said support for the X-ray tube and film holder is movable to cause said X-ray tube and said film holder to travel as aunit in opposite directions relatively to said body layer during the making of the exposure, said X-ray tube being mounted to direct the central ray therefrom always upon the same point of said plane during the making of the exposure, means to maintain the film in said film holder always parallel to said plane throughout the exposure, whereby each ray from said X-ray tube passing through any point of said plane will always fall upon the same spot of said film throughout the exposure; means relatively to move said body layer support and said shaft perpendicularly to said body layer and connected to be operated simultaneously and in unison with said movement of said X-ray tube and film holder about said shaft; and means to limit the relative movement of said support and shaft to a distance equal to the maximum thickness of a body layer which can be radiographed by the apparatus.

5. Apparatus for radiographing body layers 15 comprising an X-ray tube; a film holder, supporting means for the body layer to be radiographed located between said X-ray tube and said film holder; means to move said X-ray tube and said film holder as a unit relatively to said body layer and to a point in a plane parallel to said body layer, during the exposure to prevent production of interfering shadows on the radiograph; means relatively to move said body layer support and said point perpendicularly to said body layer connected to be operated during the exposure; and means to limit the relative movement of said support and point to a predetermined distance corresponding to the thickness of body layers to be radiographed.

HENRI CHAOUL. 

